WMS to compute time of travel, using user-defined equations or a variety of predefined equations which include the Tulsa District Lag Time Equation, the Denver Lag Time Equation, and SCS Lag Time Equation.
Figure 3.19: WMS Calculators
CASE IV: AUTOMATED METHODS USING A TIN
In addition to working with DEM terrain data, WMS also has the capability to work with TIN (triangulated irregular network) data. Similar to grid- based DEMs, TINs have also been used to characterize watersheds. TINs may be created in many ways, such as from gridded data, raw survey data, and digitizing contour data. Working with TINs is useful in that TINs provide a more precise description of the landscape than grids; however TINs are not as widely available and used as grids. TINs consist of a set of vertex points, connected by triangles, that represent scattered X, Y, and Z locations. (Nelson et al., 1999b)
For TINs to be used efficiently for basin delineation and hydrologic modeling, they need to be constructed from readily available data such as USGS